[neutron-mc] Trouble with Single_Crystal

[peter.willendrup at risoe.dk]

Hi Aaron,

 

 

I have not had time to fully investigate your problem. From an earlier attempt to use Single_crystal it seems to me that we might indeed have a problem concerning definition of the internal coordinate system.

 

Will get back to you (and this mailinglist) when I have looked more carefully.

 

Cheers,

 

Peter Willendrup

 

-- 

-----------------------------------------------

Peter Willendrup, MSc

Materials Research Department

Building 227

Risø National Laboratory

Technical University of Denmark

Frederiksborgvej 399

DK-4000 Roskilde

Denmark

 

Tel:  (+45) 4677 5862

Fax:  (+45) 4677 5758

Email: Peter.Willendrup at risoe.dk

 

-----------------------------------------------

 

>From 1 January 2007, Risø National Laboratory, the Danish Institute for

Food and Veterinary Research, the Danish Institute for Fisheries

Research, the Danish National Space Center and the Danish Transport

Research Institute have been merged with the Technical University of

Denmark (DTU) with DTU as the continuing unit. 

 

________________________________

From: neutron-mc-bounces at risoe.dk [mailto:neutron-mc-bounces at risoe.dk] On Behalf Of Aaron M. Percival
Sent: Tuesday, January 23, 2007 7:16 PM
To: 'McStas users list at neutron.risoe.dk'
Subject: [neutron-mc] Trouble with Single_Crystal

 

Hello all,

 

I'm having a little bit of trouble with the single_crystal component.  I've created a .lau file in Crystallographica to simulate an Si analyzer crystal.  I simply want to reflect a neutron beam of wavelength 2.866 A using the 311 plane (d = 1.637) of Si.  So I've set up the crystal to satisfy the Bragg condition, giving theta = 61.823, and thus 2theta = 123.646.  I put a banana shaped detector around this 2theta, and I get no reflections.

 

Here is the crystal:

 

COMPONENT analyzer = Single_crystal(

    reflections = "Si.lau", xwidth = 0.1, yheight = 0.1,

    zthick = 0.01, delta_d_d = 0, mosaic = 18, order = 0,

    p_transmit = 0, absorption = 0, incoherent = 0, ax = 5.430530,

    by = 5.430530, cz = 5.430530, aa = 90, bb = 90, cc = 90)

  AT (0, 0, 0) RELATIVE a1

  ROTATED ( 0, theta311, 0) RELATIVE sample_arm

 

Where theta311 = 61.823 relative to the incident beam.

 

Can any one offer any suggestions as to why this might not be working?

I've also attached the Si.lau file.

 

Thanks, 

 

Aaron

 

 

*************************************************

Aaron M. Percival

M.Sc. Candidate

Dept. of Physics, Engineering Physics & Astronomy

Queen's University

Kingston, Ontario, Canada, K7L 3N6

Office: 613-533-6000 ext. 74789

Fax: 613-533-6463

*************************************************

 

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